Valves are employed in a multitude of industries to control flow of liquids and/or gases. One application for such control valves appears in vehicles with stored fuel to control a vehicle's evaporative emissions resulting from fuel vapors escaping from the vehicle's fuel system. Evaporative emissions of modern vehicles are strictly regulated in many countries. To prevent fuel vapors from venting directly to the atmosphere, a majority of vehicles manufactured since the 1970s include specifically designed evaporative emissions systems. Additionally, in recent years vehicle manufacturers began developing fully sealed fuel delivery to their engines.
In a typical evaporative emissions system, vented vapors from the fuel system are sent to a purge canister containing activated charcoal. The activated charcoal used in such canisters is a form of carbon that has been processed to make it extremely porous, creating a very large surface area available for adsorption of fuel vapors and/or chemical reactions. During certain engine operational modes, with the help of specifically designed control valves, the fuel vapors are adsorbed within the canister. Subsequently, during other engine operational modes, and with the help of additional control valves, fresh air is drawn through the canister, pulling the fuel vapor into the engine where it is burned.
Emissions systems having higher operational pressures may need specialized isolation valves to handle larger pressure ranges. However, there is a desire for an isolation valve that can monitor and control vapor flow at high pressures while remaining compact and easy to install.